The narrator of the plot is the forty-year-old married Mr. Dmitri Gurov, a married man who works in a bank but had studied to become a philologist. He is described as an attractive and detached gentleman, which is essential to his charm as a ladies’ man. Although he is married with two sons and a daughter, he regularly cheats on his wife with younger women. He is dismissive of all women and internally scoffs at any such statement that does not imply that they are the inferior race. At the same time, he begrudgingly admits that he is much more at ease while he is talking to a woman than when he is conversing with a man, continually seeking their companionship. However, he is reluctant to be involved in anything remotely more than a physical relationship, choosing to cut off ties with a mistress if she gets too emotionally attached. At the start of the plot, he is at Yalta, taking a vacation from work and family. On his second week there, while strolling away by the waterfront, he notices a young woman, the titular character, taking a walk by the beach with her dog.
Since Yalta is a small town, he comes across her several more times that week. One night, while Dmitri is having his dinner, the woman takes the table beside his one, allowing him to take a closer glance at her. He deduces that she is an unhappily married woman and decides to make her his next conquest. He makes the first move by patting the dog and the woman assures him that it doesn’t bite. They go for a walk and reveal information with each other about themselves.
Dmitri learns that the woman’s name is Anna Sergeyevna and that she is from St. Petersburg. His assumption is revealed to be correct when she states that she is married and lives with her husband. She also confirms that she is going to be in Yalta for at least another month.
Anna and Dmitri spend the days together for the next week, ending their evenings by the train, watching new guests arriving at the town. One day, Dmitri asks her to accompany him on a drive. She doesn’t respond and he takes her in his arms, kissing her. They go back to her hotel and engage in an affair. After the first time, she is regretful and believes that she has sinned. Dmitri observes her reaction and compares her to all the women he engaged in sexual relationships with before. He decides that her hesitance is a cause of her age; she is too young and this is her first experience as an infidel. He doesn’t try to soothe her; rather, he waits for her to calm down. Anna takes his dismissive behavior to mean that he is now disgusted by her but he disaffirms this.
Anna shares more about her life as a wife to an officer. She is disinterested in her husband’s profession, not being able to recollect the name of the place where he is stationed. She is bored of her marriage and had regretted it since the beginning. Dmitri, bored of hearing her rants, tries to cheer her up and suggests that they go to Oreanda, near the seaside. She agrees and they take a cab there, returning to the city at dawn.
Afterward, they spend hours with each other every day, going out on lunches and taking walks. She still feels guilty about the affair and constantly demands validation from Dmitri, who tries to make her feel better by constantly complimenting Anna on her beauty and personality. Unbeknownst to him, his time with Anna starts to change Dmitri from a detached bored middle-aged man to a passionate young lover.
One day, Anna receives a letter from her husband, who asks her to come back. The lovers depart reluctantly and Dmitri is with Anna till the last moment when the train is about to leave. Anna is tearful, her eyes red from crying while Dmitri looks restrained although he too is saddened. She tells him that this will be the last time they will meet each other and after her departure, Dmitri goes back to Moscow too.
Back in Moscow, Dmitri busies himself with clubs, restaurants and the city itself in order to forget about his affair with Anna back at Yalta. He convinces himself that in one month, he won’t even be able to remember her face. However, even after a month, he cannot forget her and sees her face everywhere he goes. He is scared to admit to himself that he is in love, unsure about these surges of feelings since he has never felt like this for someone before. His work and his family cannot wake him from his depression and he is distracted all the time since he cannot confide about Anna with anyone without admitting to his affair.
During the winter, he decides to take a trip to Anna’s city and lies to his wife about his whereabouts. He books a hotel room and finds out more about where she lives. Since it is the time of the holidays, he is worried about coming across her husband if he chooses to visit her at her home. He keeps tabs on her and once, watches an old woman exit the house with Anna’s dog.
One night, he visits the theater while the opera is going on, hoping to meet Anna there. She does come to the play and Dmitri notices her there with her husband. During the intermission, when her husband is outside having a smoke, Dmitri goes up to her and greets her. She instantly turns pale and is frightened on meeting Dmitri, which attracts more attention to them among the audience. She gets up and leaves the room with Dmitri at her tail. They converse outside; Anna inquires after his intention regarding the visit and begs him to go back. It is clear that she too has been miserable since their separation and had been unsuccessful at moving on with her life. Dmitri kisses her by taking her in his arms like the way he had done the first time but she moves away, asking him to go back. Finally, they agree that if he goes back to Moscow, she will come visit him soon. She goes back in, leaving Dmitri in the snow, who stands there for a few moments after leaving for the motel.
The story shifts to Moscow where Anna arrives every two or three months to visit Dmitri. She regularly lies to her husband about the reason behind her visit, saying that she has to go for a consultation about a lady problem. She stays at a hotel called the Slavic Bazaar and sends a man to notify Dmitri of her arrival. On one such event, after having received a message from Anna, he takes his daughter to the school, intending to visit the hotel after seeing her off. The father and daughter are engaged in a conversation about the possibility of snow occurring even after the temperature is above the point of freezing. Suddenly, Dmitri reflects back on his actions and realizes that he had resorted to living a double life. One is with his family and peers, an identity that everyone is aware of and the second is with his frequent meetings with Anna. In the end, it is the second one which is more important to him, the identity that truly matters to him.
After leaving his daughter at her school, he goes to Anna and they have a passionate reunion. Anna cries and is reproachful of their fate as secret lovers. Dmitri attempts to make her stop crying and takes her in his arms. As he does so, he takes a look at the mirror and sees himself with Anna. He sees a young woman with a far older man with graying hair. He finally understands the reason why women have always been attracted to him; it is not his real appearance like the one he can see in the mirror that draws them to him but one that they have made up in their own mind. For the first time in his life, although the readers have known for quite some time, he states that he has fallen in love with Anna. Their love is not one that is fair as they are both married to other people and Dmitri has three children but it is fairly influential since it has been instrumental in changing them into different individuals.
They talk about more substantial matters such as how they intend to keep the affair a secret and how to continue this relationship amidst such hard obstacles. They assure themselves that once they have figured out the technicalities, they can live out their second identities in peace. However, they also understand that there is a long way before they can hope to achieve that pinnacle. This is just the beginning.